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Fixed bug #33 Mike Frysinger wrote: > with libsdl-1.2.9, some games (like bomberclone) started > segfaulting in Gentoo [...snip...] > the last change in the last hunk: [...snip...] > if i change the statement to read: > (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures() > bomberclone no longer segfaults on my box Alex Volkov wrote: > The test "(table[which].blit_features & GetBlitFeatures()) == > table[which].blit_features)" is correct, and the previous > "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken. I think there is potentially a slightly different cause of the above problem. During the introduction of the Altivec code, the blit_table struct field 'alpha' got changed from a straightforward enum to a bitmask, which makes perfect sense by itself. However, now the table driven blitter selection code in SDL_CalculateBlitN() can choose the wrong blitters when searching for a NO_ALPHA blitter because of the following code: int a_need = 0; ... (a_need & table[which].alpha) == a_need && When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing alpha channel bits to appear in a non-alpha destination surface. I suppose this could theoretically be an indirect cause of the segfault mentioned above. I *think* this can be fixed by changing to int a_need = NO_ALPHA;
author Sam Lantinga <slouken@libsdl.org>
date Wed, 15 Mar 2006 15:47:49 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_JoystickOpen</TITLE
><META
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><HR
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><H1
><A
NAME="SDLJOYSTICKOPEN"
></A
>SDL_JoystickOpen</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN6096"
></A
><H2
>Name</H2
>SDL_JoystickOpen&nbsp;--&nbsp;Opens a joystick for use.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN6099"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN6100"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_Joystick *<B
CLASS="FSFUNC"
>SDL_JoystickOpen</B
></CODE
>(int index);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6106"
></A
><H2
>Description</H2
><P
>Opens a joystick for use within SDL. The <TT
CLASS="PARAMETER"
><I
>index</I
></TT
> refers to the N'th joystick in the system. A joystick must be opened before it game be used.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6110"
></A
><H2
>Return Value</H2
><P
>Returns a <SPAN
CLASS="STRUCTNAME"
>SDL_Joystick</SPAN
> structure on success. <SPAN
CLASS="RETURNVALUE"
>NULL</SPAN
> on failure.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6115"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>SDL_Joystick *joy;
// Check for joystick
if(SDL_NumJoysticks()&#62;0){
  // Open joystick
  joy=SDL_JoystickOpen(0);
  
  if(joy)
  {
    printf("Opened Joystick 0\n");
    printf("Name: %s\n", SDL_JoystickName(0));
    printf("Number of Axes: %d\n", SDL_JoystickNumAxes(joy));
    printf("Number of Buttons: %d\n", SDL_JoystickNumButtons(joy));
    printf("Number of Balls: %d\n", SDL_JoystickNumBalls(joy));
  }
  else
    printf("Couldn't open Joystick 0\n");
  
  // Close if opened
  if(SDL_JoystickOpened(0))
    SDL_JoystickClose(joy);
}</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6119"
></A
><H2
>See Also</H2
><P
><A
HREF="sdljoystickclose.html"
><TT
CLASS="FUNCTION"
>SDL_JoystickClose</TT
></A
></P
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